Reactive oxygen species (ROS), notably superoxide anion (O2-) in blood vessels increases their reactivity and tone in hypertension. The kidney plays the predominant role in long-term BP regulation. Renal mechanisms of hypertension center on an increased reactivity or tone of the afferent arteriole which limits the transmission of pressure into the kidney and hence increases the set point of BP regulation together with increased release of renin and an increased re-absorption of NaCl by the tubules which underlies salt sensitivity. The focus of this proposal is on the roles of ROS in renal mechanism of hypertension. We have assembled an interactive group of integrative, microvascular and micropuncture physiologists and molecular and cellular biologist to tackle this problem. Project 1 will center on the role of ROS in modulating myogenic responses (MRs) of the mouse afferent arteriole. It compares responses in normal mice, where ROS generation enhanced MRs and the reduced renal mass model of chronic kidney disease and the angiotensin infusion model of hypertension where ROS impaired MRs. It combines direct measures of MR in isolated perfused afferent arterioles with gene arrays and RNA seq analyses on these microvessels and fluorescence quantitation of ROS, and Ca2+ using knockout and transgenic mice or mice with single kidney gene transfection or deletion. Project 2 will investigate a new paradigm of growth-factor related oxidative stress and hypertension using a mouse model of inducible activation of basic fibroblast growth factor and its interaction with specific FGF molecules and receptors. Studies combine BP and afferent arteriolar reactivity to angiotensin with cellular and molecular studies of the signaling mechanism and their interaction with ROS. Project 3 will investigate the molecular mechanisms of defense against oxidative stress in the proximal tubule that are coordinated by the dopamine D2 receptors. The new hypothesis is that D2-R signaling enhances paraoxygenase-2 which activates a transcriptional redox-regulating pathways initiated by DJ2 to inhibit NADPH oxidase-induced ROS. These are supported by the Administrative, Animal and Bioanalytical Cores.